Light emitting die (led) packages and related methods

ABSTRACT

LED packages and related methods are provided. The LED packages can include a submount having a top and bottom surface and a plurality of top electrically conductive elements on the top surface of the submount. An LED can be disposed on one of the top electrically conductive elements. The LED can emit a dominant wavelength generally between approximately 600 nm and approximately 650 nm, and more particularly between approximately 610 nm and approximately 630 nm when an electrical signal is applied to the top electrically conductive elements. A bottom thermally conductive element can be provided on the bottom surface and is not in electrical contact with the top electrically conductive elements. A lens can be disposed over the LED. The LED packages can have improved lumen performances, lower thermal resistances, improved efficiencies, and longer operational lifetimes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application relates, claims priority to and is acontinuation-in-part application from these related matters: co-pendingU.S. utility patent application Ser. No. 11/982,275, filed Oct. 31,2007; and co-pending U.S. utility patent application Ser. No.12/757,891, filed Apr. 9, 2010. The entire contents of all of the abovematters are hereby incorporated by reference herein.

TECHNICAL FIELD

The subject matter disclosed herein relates generally to light emittingdie packages and, more particularly, to light emitting die packages withimproved performance characteristics and with at least one lightemitting die operable for emitting red light or light close inwavelength to red or red-orange light.

BACKGROUND

Light emitting dies (LED or LEDs) are solid state devices that convertelectric energy to light, and generally comprise one or more activelayers of semiconductor material sandwiched between oppositely dopedlayers. When a bias is applied across the doped layers, holes andelectrons are injected into the active layer where they recombine togenerate light. As the bias or voltage is applied to the semiconductor,the energy that is used by the LED is converted into light energy, andthe light is emitted from the active layer and from all surfaces of theLED. In order to use an LED chip in a circuit or other like arrangement,it is known to enclose an LED chip in a package to provide environmentaland/or mechanical protection, color selection, focusing and the like. AnLED package can also include electrical leads, contacts or traces forelectrically connecting the LED package to an external circuit. In atypical LED package, an LED chip can be mounted on a reflective cup bymeans of a solder bond or conductive epoxy. One or more wire bonds canconnect the ohmic contacts of the LED chip to leads, which may beattached to or integral with the reflective cup. The reflective cup maybe filled with an encapsulant material containing a wavelengthconversion material such as a phosphor. Light emitted by the LED at afirst wavelength may be absorbed by the phosphor, which may responsivelyemit light at a second wavelength. The entire assembly can then beencapsulated in a clear protective resin, which may be molded in theshape of a lens to collimate the light emitted from the LED chip. Whilethe reflective cup may direct light in an upward direction, opticallosses may occur when the light is reflected (i.e. some light may beabsorbed by the reflector cup instead of being reflected). In addition,heat retention may be an issue for such a package, since it may bedifficult to extract heat through the leads.

A conventional LED package may be more suited for high power operationsin one or more LED chips are mounted onto a carrier such as a printedcircuit board (PCB) carrier, substrate or submount. Such a package canalso generate more heat. A metal reflector mounted on the submount cansurround the LED chip(s) and can reflect light emitted by the LED chipsaway from the package. The reflector can also provide mechanicalprotection to the LED chips. One or more wirebond connections can bemade between ohmic contacts on the LED chips and electrical traces onthe carrier. The mounted LED chips can then be covered with anencapsulant, which may provide environmental and mechanical protectionto the chips while also acting as a lens. The metal reflector istypically attached to the carrier by means of a solder or epoxy bond.

While such a package may have certain advantages for high poweroperation, there may be a number of potential problems associated withusing a separate metal piece as a metal reflector. For example, smallmetal parts may be difficult to manufacture repeatable with a highdegree of precision at a reasonable expense. In addition, since thereflector is typically affixed to a carrier using an adhesive, severalmanufacturing steps may be required to carefully align and mount thereflector, which may add to the expense and complexity of themanufacturing process for such packages.

For higher powered operation, it may also be difficult to dissipate heatgenerated by the LED chip. This can be true for packages employing LEDsof specific light ranges, for example, LEDs that emit red and/orred-orange light. Submounts can be made of materials such as ceramicsthat are robust but do not efficiently conduct or dissipate heat whichcan result in reduced efficiency and output of the LED package as wellas reduced lifetime or failure of the package. Other factors involved inusing conventional packages can also reduce and/or limit the lumenperformance, efficiency and/or lifetime of such LED packages.

SUMMARY

In accordance with this disclosure, novel LED packages and relatedmethods are provided. In particular, LED packages and related methodsare provided with at least one LED operable for emitting a dominantwavelength of, for example, generally between approximately 600 nm andapproximately 650 nm, and more particularly between approximately 610 nmand approximately 630 nm. It is, therefore, an object of the disclosureherein to provide novel packages for LEDs and methods as described forexample in further detail herein.

These and other objects as can become apparent from the disclosureherein are achieved, at least in whole or in part, by the subject matterdescribed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present subject matter includingthe best mode thereof to one of ordinary skill in the art is set forthmore particularly in the remainder of the specification, includingreference to the accompanying figures, in which:

FIG. 1 is a top plan view illustrating an embodiment of a light emittingdiode (LED) package according to the subject matter disclosed herein;

FIG. 2 is a side view illustrating the embodiment of the LED packageaccording to FIG. 1;

FIG. 3 is a bottom plan view illustrating the embodiment of the LEDpackage according to FIG. 1;

FIG. 4 is a top perspective view illustrating the embodiment of the LEDpackage according to FIG. 1;

FIG. 5 is a bottom perspective view illustrating the embodiment of theLED package according to FIG. 1;

FIG. 6 is an exploded perspective view illustrating the embodiment ofthe LED package according to FIG. 1;

FIG. 7 is a top plan view illustrating a portion of an embodiment of apackage for an LED according to the subject matter disclosed herein;

FIG. 8 is a bottom plan view illustrating the embodiment of the packagefor an LED according to FIG. 7; and

FIG. 9 is a top plan view illustrating the embodiment of the package foran LED according to FIG. 7 with an embodiment of a solder mask disposedthereon according to the subject matter disclosed herein.

DETAILED DESCRIPTION

Reference will now be made in detail to possible aspects or embodimentsof the subject matter herein, one or more examples of which are shown inthe figures. Each example is provided to explain the subject matter andnot as a limitation. In fact, features illustrated or described as partof one embodiment can be used in another embodiment to yield still afurther embodiment. It is intended that the subject matter disclosed andenvisioned herein covers such modifications and variations.

As illustrated in the various figures, some sizes of structures orportions are exaggerated relative to other structures or portions forillustrative purposes and, thus, are provided to illustrate the generalstructures of the present subject matter. Furthermore, various aspectsof the subject matter disclosed herein are described with reference to astructure or a portion being formed on other structures, portions, orboth. As will be appreciated by those of skill in the art, references toa structure being formed “on” or “above” another structure or portioncontemplates that additional structure, portion, or both may intervene.References to a structure or a portion being formed “on” anotherstructure or portion without an intervening structure or portion may bedescribed herein as being formed “directly on” the structure or portion.Similarly, it will be understood that when an element is referred to asbeing “connected”, “attached”, or “coupled” to another element, it canbe directly connected, attached, or coupled to the other element, orintervening elements may be present. In contrast, when an element isreferred to as being “directly connected”, “directly attached”, or“directly coupled” to another element, no intervening elements arepresent.

Furthermore, relative terms such as “on”, “above”, “upper”, “top”,“lower”, or “bottom” are used herein to describe one structure's orportion's relationship to another structure or portion as illustrated inthe figures. It will be understood that relative terms such as “on”,“above”, “upper”, “top”, “lower” or “bottom” are intended to encompassdifferent orientations of the device in addition to the orientationdepicted in the figures. For example, if the device in the figures isturned over, structure or portion described as “above” other structuresor portions would now be oriented “below” the other structures orportions. Likewise, if devices in the figures are rotated along an axis,structure or portion described as “above”, other structures or portionswould now be oriented “next to” or “left” of the other structures orportions. It is understood that these terms are intended to encompassdifferent orientations of the device in addition to the orientationdepicted in the figures. Like numbers refer to like elements throughout.

Light emitting devices according to package embodiments described hereincan comprise light emitting devices that emit a red or red-orange light,for example, light having a dominant wavelength generally betweenapproximately 600 nm and approximately 650 nm, and, for example andwithout limitation, more specifically between approximately 610 nm andapproximately 630 nm. Light emitting devices according to embodimentsdescribed herein may also comprise group III-V nitride (e.g., galliumnitride) based light emitting diodes (LEDs) or lasers fabricated on agrowth substrate, for example, silicon carbide substrate, such as thosedevices manufactured and sold by Cree, Inc. of Durham, N.C. For example,Silicon carbide (SiC) substrates/layers discussed herein may be 4Hpolytype silicon carbide substrates/layers. Other silicon carbidecandidate polytypes, such as 3C, 6H, and 15R polytypes, however, may beused. Appropriate SiC substrates are available from Cree, Inc., ofDurham, N.C., the assignee of the present subject matter, and themethods for producing such substrates are set forth in the scientificliterature as well as in a number of commonly assigned U.S. patents,including but not limited to U.S. Pat. No. Re. 34,861; U.S. Pat. No.4,946,547; and U.S. Pat. No. 5,200,022, the disclosures of which areincorporated by reference herein in their entireties.

As used herein, the term “Group III nitride” refers to thosesemiconducting compounds formed between nitrogen and one or moreelements in Group III of the periodic table, usually aluminum (Al),gallium (Ga), and indium (In). The term also refers to binary, ternary,and quaternary compounds such as GaN, AlGaN and AlInGaN. The Group IIIelements can combine with nitrogen to form binary (e.g., GaN), ternary(e.g., AlGaN), and quaternary (e.g., AlInGaN) compounds. These compoundsmay have empirical formulas in which one mole of nitrogen is combinedwith a total of one mole of the Group III elements. Accordingly,formulas such as AlxGa1−xN where 1>x>0 are often used to describe thesecompounds. Techniques for epitaxial growth of Group III nitrides havebecome reasonably well developed and reported, for example, in commonlyassigned U.S. Pat. No. 5,210,051, U.S. Pat. No. 5,393,993, and U.S. Pat.No. 5,523,589, the disclosures of which are hereby incorporated byreference herein in their entireties.

Although various embodiments of LEDs disclosed herein comprise a growthsubstrate, it will be understood by those skilled in the art that thecrystalline epitaxial growth substrate on which the epitaxial layerscomprising an LED are grown may be removed, and the freestandingepitaxial layers may be mounted on a substitute carrier substrate orsubmount which may have better thermal, electrical, structural and/oroptical characteristics than the original substrate. The subject matterdescribed herein is not limited to structures having crystallineepitaxial growth substrates and may be used in connection withstructures in which the epitaxial layers have been removed from theiroriginal growth substrates and bonded to substitute carrier substrates.

Group III nitride based LEDs according to some embodiments of thepresent subject matter, for example, may be fabricated on growthsubstrates (such as a silicon carbide substrates) to provide horizontaldevices (with both electrical contacts on a same side of the LED) orvertical devices (with electrical contacts on opposite sides of theLED). Moreover, the growth substrate may be maintained on the LED afterfabrication or removed (e.g., by etching, grinding, polishing, etc.).The growth substrate may be removed, for example, to reduce a thicknessof the resulting LED and/or to reduce a forward voltage through avertical LED. A horizontal device (with or without the growthsubstrate), for example, may be flip chip bonded (e.g., using solder) toa carrier substrate or printed circuit board (PCB), or wire bonded. Avertical device (with or without the growth substrate) may have a firstterminal solder bonded to a carrier substrate, mounting pad, or PCB anda second terminal wire bonded to the carrier substrate, electricalelement, or PCB. Examples of vertical and horizontal LED chip structuresare discussed by way of example in U.S. Publication No. 2008/0258130 toBergmann et al. and in U.S. Publication No. 2006/0186418 to Edmond etal., the disclosures of which are hereby incorporated by referenceherein in their entireties.

Solid state light LEDs may be used individually or in combinations,optionally together with one or more luminescent materials (e.g.,phosphors, scintillators, lumiphoric inks) and/or filters, to generatelight of desired perceived colors (including combinations of colors thatmay be perceived as white).

Inclusion of luminescent (also called ‘lumiphoric’) materials in LEDdevices may be accomplished by adding such materials to encapsulants,adding such materials to lenses, or by direct coating onto LEDs. Othermaterials, such as dispersers and/or index matching materials may bedisposed in such encapsulants.

One or more of the LEDs can be coated, at least partially, with one ormore phosphors with the phosphors absorbing at least a portion of theLED light and emitting a different wavelength of light such that the LEDemits a combination of light from the LED and the phosphor. In oneembodiment, such an LED emits a white light combination of LED andphosphor light. The LED can be coated and fabricated using manydifferent methods, with one suitable method being described in U.S.patent application Ser. Nos. 11/656,759 and 11/899,790, both entitled“Wafer Level Phosphor Coating Method and Devices Fabricated UtilizingMethod”, and both of which are incorporated herein by reference. In thealternative, LEDs can be coated using other methods such anelectrophoretic deposition (EPD), with a suitable EPD method describedin U.S. patent application Ser. No. 11/473,089 entitled “Close LoopElectrophoretic Deposition of Semiconductor Devices”, which is alsoincorporated herein by reference. It is understood that LED devices andmethods according to the present subject matter can also have multipleLEDs of different colors, one or more of which may be white emitting.

The disclosure herein is directed to compact, simple and efficient LEDpackages. Different embodiments can comprise one or more high power LEDsthat typically operate at elevated temperatures. Packages according tothe disclosure herein can include features to provide for improvedthermal management, increased efficiency, greater luminance performanceand longer life for the LED and LED package. The packages according tothe disclosure herein can also comprise a lens molded directly over theone or more LEDs to protect the LED while still allowing for efficientemission characteristics.

Although the terms first, second, etc. may be used herein to describevarious elements, components, regions, layers and/or sections, theseelements, components, regions, layers and/or sections should not belimited by these terms. These terms are only used to distinguish oneelement, component, region, layer or section from another region, layeror section. Thus, a first element, component, region, layer or sectiondiscussed below could be termed a second element, component, region,layer or section without departing from the teachings of the disclosureherein.

Embodiments of the subject matter of the disclosure are described hereinwith reference to schematic illustrations of idealized embodiments. Assuch, variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances are expected.Embodiments of the subject matter disclosed herein should not beconstrued as limited to the particular shapes of the regions illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. A region illustrated or described as square orrectangular will typically have rounded or curved features due to normalmanufacturing tolerances. Thus, the regions illustrated in the figuresare schematic in nature and their shapes are not intended to illustratethe precise shape of a region of a device and are not intended to limitthe scope of the subject matter disclosed herein.

The subject matter of disclosure herein can be used in and/or with manydifferent solid state emitters with the embodiments below beingdescribed in relation to LEDs, and in particular to red emitting LEDsand LED packages. It is understood that the disclosure herein can alsouse other solid state emitter packages beyond the embodiment shown. Thedisclosure herein can also be used with multiple emitter packages, suchas LED packages having more than one LED. As stated above, other LEDs,such as white emitting LEDs, can be used with the red emitting LEDs foruse in general lighting applications. The disclosure herein can also beused in any application wherein a conversion material is used todown-convert the wavelength of light from an emitter, and the discussionof the disclosure herein with reference to the following embodimentshould not be construed as limiting to that particular embodiment orsimilar embodiments.

FIGS. 1 through 6 show one embodiment of a package for an LED generallydesignated 10 according to the disclosure herein generally comprising asubstrate/submount (“submount”) 12 with one or more LEDs 14 emitting thesame or different colors. In the embodiment shown, a single LED ormultiple LEDS can be mounted on submount 12. Submount 12 can comprise aceramic submount. In the embodiment shown, LED 14 as shown herein canrepresent a single LED or multiple LEDs and at least one of the LEDs canemit red or red-orange light. For example, at least one of the LEDs cangenerate or emit a dominate wavelength of generally betweenapproximately 600 nm and approximately 650 nm, or more particularlybetween approximately 610 nm and approximately 630 nm. The LEDs can havemany different semiconductor layers arranged in different ways.

LED 14 can comprise a conductive current spreading structure (not shown)and can be mounted on wire bond pads on its top surface, both of whichcan be made of a conductive material and can be deposited using knownmethods. Some materials that can, for example, be used for theseelements include Au, Cu, Ni, In, Al, Ag or combinations thereof andconducting oxides and transparent conducting oxides. The currentspreading structure can generally comprise conductive fingers (notshown) arranged in a grid on LED 14 with the fingers spaced to enhancecurrent spreading from wire bond pads into the LED's top surface. Inoperation, an electrical signal is applied to LEDs 14, such as through awire bond as described below, and the electrical signal spreads throughthe fingers of the current spreading structure and the top surface intoLED 14. Current spreading structures are often used in LEDs where thetop surface is a p-type material, but they can also be used for n-typematerials.

One or more of LEDs represented by LED 14 can be coated with one or morephosphors with the phosphors absorbing at least some of the LED lightand emitting a different wavelength of light such that the LED emits acombination of light from LED 14 and the phosphor. At least one of theLEDs can be configured to emit red or red-orange light. In someembodiments, an LED can be constructed to emit a white light combinationof LED and phosphor light. Alternatively, the LEDs can be coated usingother methods such an electrophoretic deposition (EPD). It is understoodthat LED packages according to the disclosure herein can also havemultiple LEDs of different colors, such as white emitting LEDs inadditional to one or more red and/or red-orange emitting LEDs. Submount12 can have a top surface 16 and a bottom surface 18 and can be formedof many different materials. Materials for submount 12 can beelectrically insulating. Suitable materials can comprise, but are notlimited to, ceramic materials such as aluminum oxide, aluminum nitrideor organic insulators like polyimide (PI) and polyphthalamide (PPA). Insome embodiments, submount 12 can comprise a printed circuit board(PCB), sapphire or silicon or any other suitable material, such asT-Clad thermal clad insulated substrate material, available from TheBergquist Company of Chanhassen, Minn. For PCB embodiments different PCBtypes can be used such as standard FR-4 PCB, metal core PCB, or anyother type of printed circuit board.

As stated above, submount 12 can comprise a ceramic submount. In someembodiments, submount 12 can comprise aluminum nitride (AlN). In packageembodiments that use AlN as a material for submount 12 to which one ormore red or red-orange LEDs are attached and the polarity is reversedsuch that the N-cladding is below the multi-quantum well and theP-cladding is above the multi-quantum well, the minimum luminous flux ata current of approximately 350 mA can be higher than in conventionalpackages the include red or red-orange LEDs.

For an LED 14 in package 10 that can emit light having a dominantwavelength of, for example, approximately 600 nm to approximately 650nm, and more particularly approximately 610 nm to approximately 630 nm,luminance performance can be such that the minimum luminous flux can beapproximately 90 lumens (lm) or greater. LED 14 when attached to package10 in some embodiments can emit light having a dominant wavelength ofapproximately 610 nm to approximately 630 nm and a luminance performancesuch that the luminous flux can be approximately 100 lm or greater. Insome embodiments, for example, LED 14 when attached to package 10 canemit light having a dominant wavelength of approximately 610 nm toapproximately 630 nm and a luminance performance such that the luminousflux can be approximately 95 lm or greater. Packages 10 that use othersubstrate materials in submount 12 other than AlN and do not have thepolarity reversed may also facilitate an LED that has a dominantwavelength of, for example, approximately 610 to approximately 630 nm toachieve a luminance performance of a luminous flux of approximately 90lm or greater. While the minimum luminous flux produced above is with acurrent of approximately 350 mA, it is understood that a higher drivecurrent can yield a higher luminous flux.

Using AlN as a substrate material for submount 12 in accordance with thedisclosure herein can give improved thermal performance. In turn,improved thermal performance can give better reliability as well as lessshift of the wavelength and less of a drop in lumens with increasingtemperature. Using AlN as a substrate material for submount 12 can allowpackage 10 and any system in which it is used to run at a higher heatsink (submount) temperature for the same performance or at the same heatsink (submount) temperature for the same or greater performance. LEDSthat are driven at higher temperatures and are able to thermallyaccommodate the higher temperatures can lead to a brighter output fromLED 14 and package 10, since LEDs 14 can be driven harder or cheapersince a corresponding submount 12 can be easier to build. Running athigher current can lead to brighter output.

In manufacturing LEDs, the LEDs are formed on a larger semiconductorsheet or wafer. Some of these newly manufactured LEDs will not work aswell as the majority of the other LEDs. These newly manufactured LEDscan be passed through a screening process that can quickly identifyand/or predict which LED 14 will have the best reliability and should beselected for inclusion in a package 10.

As noted, many materials can be used to fabricate the submount element.In various embodiments, it is desirable to have a submount that is agood electrical insulator with low thermal resistance or high thermalconductivity (e.g., aluminum nitride). Some materials that may be usedhave a thermal conductivity of approximately 30 W/mK or higher, such aszinc oxide (ZnO). Other acceptable materials have thermal conductivitiesof approximately 120 W/mK or higher, such as aluminum nitride (AlN)which has a thermal conductivity that can range from approximately 140W/mK to approximately 180 W/mK. In terms of thermal resistance, someacceptable materials have a thermal resistance of approximately 2° C./Wor lower. Thus, package 10, for example, through the selection of thematerials for the submount, can have a reduced thermal resistance. Othermaterials may also be used that have thermal characteristics outside theranges discussed herein.

Top surface 16 of submount 12 can comprise patterned conductive featuressuch as top electrically conductive elements that can comprise a dieattach pad 20 with an integral first contact pad 22. A second contactpad 24 that is also considered a top electrically conductive element canalso be included on top surface 16 with LED 14 mounted approximately ata center of attach pad 20. These electrically conductive elements canprovide conductive paths for electrical connection to LED 14 using knowncontacting methods. LED 14 can be mounted to attach pad 20 using knownmounting methods and material such as using conventional soldermaterials that may or may not contain a flux material or dispensedpolymeric materials that may be thermally and electrically conductive.As noted above, LED 14 can be attached to attach pad 20 with thepolarity of LED 14 reversed such that the N-cladding of LED 14 is belowthe multi-quantum well and the P-cladding of LED 14 is above themulti-quantum well.

In some embodiments, LED 14 can be mounted on attach pad 20 with agold-tin (Au/Sn) solder. The Au/Sn solder can be deposited on LED 14.For example, the Au/Sn solder can be deposited on a bottom surface 14Aof LED 14 and can reside between LED 14 and attach pad 20.Alternatively, The Au/Sn solder can be deposited on attach pad 20. Forexample, the Au/Sn solder can be deposited on attach pad 20 and canreside between LED 14 and attach pad 20.

A robust die attach process can help to achieve low electricalresistance, low thermal resistance and good mechanical and electricalintegrity. A “flux-eutectic” die attach method can be used in attachingLEDs 14 to attach pad 20 with an Au/Sn solder. In such an attach method,no external force needs to be applied throughout the process. Such a dieattach method can help prevent squeeze-out of the die attach metalduring attachment, thereby reducing the risk of forming a Schottkycontact in the package 10, for example with an n-substrate. During chipfabrication, an 80% Au/20% Sn eutectic metal layer can be deposited onbottom surface 14A of LED 14. The melting temperature of the 80% Au/20%Sn metal can be, for example, about 282° C. During assembly, a verysmall volume of flux can be placed on attach pad 20 by pin transfer orother precision dispense method, and LED 14 can be placed into the flux.For example, a no-clean flux (such as Alpha Metals UP78) can bedispensed onto attach pad 20 via pin transfer with a dot size ofapproximately 200 um. After die placement, attach pad 20 can be heatedto a predetermined temperature for a set amount of time. For example,attach pad 20 can be heated to about 305° C. for about 5-8 seconds withdirect heating method or hot air guns to reflow the Au/Sn metal.Subsequent cleaning in isopropyl alcohol in an ultrasonic bath canremove flux residue prior to wirebonding and encapsulation. For example,about a 15-minute ultrasonic isopropyl alcohol clean bath can be used.

When using such a die attach process, careful control of flux dispensevolume can help to minimize risk of LED 14 movement during reflow. Inaddition, LED 14 can be placed through the flux and in contact withattach pad 20 prior to reflow. The peak temperature can be about 20° C.to about 30° C. above the melting temperature of the solder that isused. An RMA flux can result in good shear strengths; however, using toomuch flux can cause poor melting of the Au/Sn. The type of flux, theamount of flux used, and the reflow time and temperatures can be factorsthat should be understood and controlled by the user to optimize dieattach results and long term reliability of the package 10.

Attach pad 20 and first and second contact pads 22, 24 can comprisedifferent materials. Attach pad 20 and first and second contact pads 22,24 can comprise, for example, metals or other conductive materials. Insome embodiments, pads 20, 22, 24 comprise copper deposited using knowntechniques such as plating. In a typical plating process a titaniumadhesion layer and copper seed layer are sequentially sputtered onto asubstrate. Then, approximately 75 microns of copper is plated onto thecopper seed layer. The resulting copper layer being deposited can thenbe patterned using standard lithographic processes. In otherembodiments, the layer can be sputtered using a mask to form the desiredpattern.

In some embodiments according to the disclosure herein some of theconductive elements can include only copper, with others of the elementsincluding additional materials. For example, attach pad 20 can be platedor coated with additional metals or materials to make attach pad 20 moresuitable for mounting one or more LEDs 14. For example, attach pad 20can be plated with adhesive or bonding materials, or reflective andbarrier layers.

A gap 26 as seen in FIGS. 1, 4, and 6 can be included between second pad24 and attach pad 20 down to the surface of submount 12. Gap 26 canprovide electrical isolation between attach pad 20 and second pad 24. Anelectrical signal can be applied to LED 14 through second pad 24 andfirst pad 22, with the electrical signal on first pad 22 passingdirectly to LED 14 through attach pad 20 and the signal from second pad24 passing into LED 14 through wire bonds or other conductive elements(not shown). Gap 26 can also provide electrical isolation between secondpad 24 and attach pad 20 to prevent shorting of the signal applied toLED 14.

In some embodiments, an electrical signal can be applied to package 10by providing external electrical contact to first and second bond pads22, 24 such as by solder contacts or other conductive paths to a PCB. Inthe embodiment shown, LED package 10 can be arranged for mounting usingsurface mount technology and having internal conductive paths. LEDpackage 10 can comprise first and second surface mount pads 30, 32,respectively, as seen in FIGS. 3 and 5 that can be formed on backsurface 18 of submount 12. First and second surface mount pads 30, 32can be at least partially in alignment with first and second contactpads 22, 24, respectively. Conductive vias 34 can be formed throughsubmount 12 between first mounting pad 30 and first contact pad 22, suchthat, when a signal is applied to first mounting pad 30, the signal isconducted to first contact pad 22. Similarly, conductive vias 34 can beformed between second mounting pad 32 and second contact pad 24 toconduct an electrical signal therebetween as well. First and secondmounting pads 30, 32 allow for surface mounting of LED package 10. Insuch embodiments, the electrical signal can be applied to LED 14 acrossfirst and second mounting pads 30, 32. Vias 34 and mounting pads 30, 32can be made of many different materials using different techniques,including deposition methods that can be used for attach and contactpads 20, 22, 24.

It is understood that mounting pads 30, 32 and vias 34 can be arrangedin many different ways and can have many different shapes and sizes. Itis also understood that instead of vias, one or more conductive tracescan be provided on the surface of the submount between the mounting padsand contact pads, such as along a side surface of submount 12.

A solder mask 36, as shown for example in FIGS. 1, 2 and 4, made ofconventional materials can be included on top surface 16 of submount 12,at least partially covering attach pad 20 and first and second contactpads 22, 24, and at least partially covering gap 26. Solder mask 36 canprotect these features during subsequent processing steps, which caninclude the mounting of LED 14 to attach pad 20 and wire bonding of LED14 to package 10. During such steps, there can be a danger of solder orother materials depositing in undesired areas, which can result indamage to the areas or result in electrical shorting. Solder mask 36 canserve as an insulating and protective material that can reduce orprevent these dangers. Solder mask 36 can comprise an opening formounting LED 14 to attach pad 20 and for attaching wire bonds (notshown) to second contact pad 24. Solder mask 36 can also comprise sideopenings 38 to allow convenient electrical access to contact pads 22, 24for testing package 10 during fabrication. Solder mask 36 and/or attachpad 20 can also have alignment holes that provide for alignment duringfabrication of package 10 and can also allow for alignment when mountedin place by an end user.

In some embodiments, solder mask 36 and/or attach pad 20 can be providedwith a symbol or indicator 36A to illustrate which side of LED package10 should be coupled to a positive or negative signal that can beapplied to package 10. Symbol 36A can ensure accurate mounting of LEDpackage 10 to a PCB or other fixture, whether by machine or hand. As inthe embodiment shown, symbol 36A can comprise a plus (+) sign over firstcontact pad 22, indicating that package 10 should be mounted with thepositive of the signal coupled to first mounting pad 30. The negative ofthe signal can then be coupled to second mounting pad 32. It isunderstood that many different symbol types can be used and that asymbol can also be included over second conductive pad 24 in addition orin the alternative to symbol 36A. It is also understood that the symbolscan be placed in other locations other than solder mask 36.

Package 10 can also comprise elements to protect against damage fromelectrostatic discharge (ESD). Different elements can be used which canbe on-chip. Examples of different elements can include, but are notlimited to, various vertical silicon (Si) Zener diodes, different LEDsarranged in parallel and reverse biased to LED 14, surface mountvaristors and/or lateral Si diodes. It is noted that solder mask 36 caninclude an opening for an ESD diode (not shown) if such a diode isdesired, so that it can be mounted to attach pad 20. An arrangement withan LED 14 and the ESD diode can allow excessive voltage and/or currentpassing through the LED package 10 from an ESD event to pass through theESD diode instead of LED 14, protecting LED 14 from damage. Differentmounting materials and methods can be used such as those used to mountLED 14 to attach pad 20. One or more wire bonds (not shown) can also beincluded between the solder mask opening in the second contact pad 24and LED 14. Wire bonds (not shown) for both LED 14 and the ESD diode canbe applied using known methods and can comprise known conductivematerials, with a suitable material being, for example, gold (Au). It isunderstood that LED package 10 according to the disclosure herein can beprovided without an ESD element/diode or with an ESD element/diode thatis external to LED package 10.

As described above, in conventional packages, heat typically does notspread efficiently into the submount, particularly those made ofmaterials such as ceramic. In some embodiments, when an LED is providedon an attach pad that extends generally only under the LED, heat doesnot spread through most of the submount, and is generally concentratedto the area just below the LED. This can cause overheating of the LEDwhich can limit the operating power level for the LED package.

Thermal resistance, however, in package 10 is lower than in other,conventional packages. This lower thermal resistance can lead to loweroperating temperatures for the LED by allowing quicker heat dissipationtherefrom. Such lower thermal resistance can thus lead to greater lumenperformance of the attached LED(s) and a greater lifetime for theLED(s). As above, for example, thermal resistance can be lower forpackage 10 with submount 12 comprising aluminum nitride (AlN) ascompared to similarly sized chips with ceramic submounts. Package 10 canhave a thermal resistance of approximately 3° C./Watt or less. In someembodiments, package 10 can have a thermal resistance of approximately2.5° C./Watt or less. Pads 20, 22, 24 can provide extending thermallyconductive paths to laterally conduct heat away from LED 14 such that itcan spread to other areas of submount 12 beyond the areas just below LED14 to further improve heat dissipation. Attach pad 20 can cover more ofthe surface of submount 12 than LED 14, with attach pad 20, for example,extending from the edges of LED 14 toward the edges of submount 12. Asin the embodiment shown, attach pad 20 can be generally circular and canextend radially from LED 14 toward the edges of submount 12. A portionof attach pad 20 can intersect with first and second contact pads 22,24, with gap 26 separating part of attach pad 20 adjacent to secondcontact pad 24. It is understood that attach pad 20 can be many othershapes and in some embodiments, for example, it can extend to the edgeof submount 12.

Contact pads 22, 24 can also cover the surface of submount 12 extendingout from vias 34. For example, contact pads 22, 24 can cover the areabetween vias 34 and the edges of the submount 12. By extending pads 20,22 and 24 in this manner, the heat spreading from LED 14 can beimproved. Thermal dissipation of heat generated in LED 14 can thus beimproved, which improves the operating life and allows for higheroperating power for LED 14 and LED package 10. Pads 20, 22, and 24 cancover different percentages of top surface 16 of submount 12, with atypical coverage area being greater than 50%. In LED package 10, pads20, 22 and 24 can, for example, cover approximately 70% of submount 12.In other embodiments, the coverage area can, for example, be greaterthan 75%.

As shown for example beginning with FIGS. 3 and 5, LED package 10 canfurther comprise a bottom thermally conductive element that can comprisethermal pad 40 on back surface 18 of submount 12 between first andsecond mounting pads 30, 32. Thermal pad 40 can be made of a heatconductive material and can be in at least partial vertical alignmentwith LED 14. In some embodiments, thermal pad 40 may not be inelectrical contact with the elements on top surface 16 of submount 12 orfirst and second mounting pads 30, 32 on back surface 18 of submount 12.Although heat from the LED can be laterally spread over top surface 16of submount 12 by attach pad 20 and pads 22, 24, more heat can pass intosubmount 12 directly below and around LED 14 with such placement ofthermal pad 40. Thus, thermal pad 40 can assist with this dissipation byallowing this heat to spread into thermal pad 40 where it can dissipatemore readily. It is also noted that the heat can conduct from topsurface 16 of submount 12, through vias 34, where the heat can spreadinto first and second mounting pads 30, 32 where it can also dissipate.For package 10 used in surface mounting, the thickness of thermal pad 40and first and second pads 30, 32 as seen in FIGS. 3 and 5 can beapproximately the same such that all three make contact to a lateralsurface such as a PCB. Thermal pad 40 can be attached to a larger heatsink if desired.

Thermal pad 40 can comprise a metal that may or may not be electricallyconductive. In one aspect, thermal pad 40 can be electrically attachedto at least one of first contact pad 22 or second contact pad 24. Inanother aspect, thermal pad 40 can be electrically neutral allowing oneor more LEDs to be configured in an array using a common metal substratewithout risk of electrical shorting, thus simplifying thermal design.

Solder dams 28 (shown in dotted lines) can be included around the areaof attach pad 20 for mounting of LED 14. Solder dams 28 can help centerLED 14 to reduce movement of LED 14 from the mounting area while themounting solder is in liquid form. When the liquid solder encounters anyone of dams 28, movement can be slowed or stopped. Thereby, the movementof LED 14 on attach pad 20 can be reduced until the solder hardens.

An optical element or lens 50 can be formed on top surface 16 ofsubmount 12, over LED 14. Lens 50 can provide both environmental and/ormechanical protection. Lens 50 can be in different locations on the topsurface 16. As shown, lens 50 can be located with LED 14 placed atapproximately a center of a base of lens 50. In some embodiments, lens50 can be formed in direct contact with the LED and top surface 16 onsubmount 12. In other embodiments, there may be an intervening materialor layer between LED 14 and top surface 16. Direct contact to LED 14 canprovide certain advantages such as improved light extraction and ease offabricating. In particular, lens 50 can be molded onto submount 12.

Lens 50 can be molded using different molding techniques. Lens 50 can bemany different shapes depending on the desired shape of the lightoutput. One suitable shape as shown is hemispheric, with some examplesof alternative shapes being ellipsoid bullet, flat, hex-shaped andsquare. Many different materials can be used for lens 50 such assilicones, plastics, epoxies or glass, with a suitable material beingcompatible with molding processes. Silicone is suitable for molding andprovides suitable optical transmission properties. For example, asilicone can be selected that has a high refractive Index and hightransparency. It can also withstand subsequent reflow processes and doesnot significantly degrade over time. It is understood that lens 50 canalso be textured to improve light extraction or can contain materialssuch as phosphors or scattering particles. Lens 50 can vary in size. Thesize of the lens can vary based on the size of package 10, inparticular, submount 12. For example, an approximately 3.5 mm byapproximately 3.5 mm submount 12 can have a lens 50 can have a radiussize of approximately 1.275 mm or greater. In some embodiments, anapproximately 3.5 mm by approximately 3.5 mm submount 12 can have a lens50 can have a radius size of approximately 1.275 mm. Lens 50 can forexample have a radius size of between approximately 1.275 mm toapproximately 1.53 mm. Package 10 can also comprise a protective layer52 covering top surface 16 of submount 12 between lens 50 and edge ofsubmount 12. Layer 52 can provide additional protection to the elementson top surface 16 to reduce damage and contamination during subsequentprocessing steps and use. Protective layer 52 can be formed duringformation of lens 50 and can comprise the same material as lens 50. Itis understood, however, that package 10 can also be provided withoutprotective layer 52. For example, a technique for molding lens 50 and/orprotective layer 52 can include those described in U.S. patentapplication Ser. No. 11/982,275 entitled “Light Emitting Diode Packageand Method of Fabricating Same”, which, as stated above, is alsoincorporated herein by reference.

Lens 50 can also be able to withstand certain sheer forces before beingdisplaced from submount 12. In one embodiment, the lens can withstandapproximately a 1 kilogram (kg) or more sheer force. Embodiments ofpackage 10 using silicones that are harder after curing and have ahigher durometer reading, such as Shore A 70 or higher, in molding lens50 may tend to better withstand sheer forces. Properties such as highadhesion and high tensile strength can also contribute to the ability oflens 50 to withstand sheer forces. The lens arrangement of LED package10 can easily be adapted for use with secondary lens or optics that canbe included over lens 50 by the end user to facilitate beam shaping.These secondary lenses are generally known in the art, with many of thembeing commercially available.

Thus, LED packages 10 as described above can be used with at least oneLED 14 that can emit a dominant wavelength generally betweenapproximately 600 nm and approximately 650 nm, and more particularlybetween approximately 610 nm and approximately 630 nm, when anelectrical signal is applied to package 10, thereby emitting a red orred-orange light. When a current of approximately 350 mA is applied topackage 10, package 10 can be configured to have a lumen performance ofa minimum luminous flux of approximately 90 lm or greater. In someembodiments, package 10 can be configured to have a lumen performance ofa minimum luminous flux of approximately 100 lm or greater. For example,a package 10 in which LED 14 generates a dominant wavelength betweenapproximately 610 nm and approximately 630 nm when an electrical signalcan be applied to top electrically conductive elements such as contactpads 22, 24 can be configured to have a minimum luminous flux that canbe approximately 90 lm or greater. Such an LED package 10 can have, forexample, a luminance performance with a minimum luminous flux ofapproximately 95 lm or greater even in package 10. Wavelength shift canbe approximately 0.5 nanometers for a current of approximately 1,000milliamps.

The size of submount 12 and package 10 can vary depending on differentfactors, such as, for example, the size of LED(s) 14. Package 10 canhave a height H. For example, height H of package 10 can beapproximately 2.0 mm as measured between a top of lens 50 and bottomsurface 18 of submount 12 as shown in FIG. 2. Package 10 can, as shownin FIG. 1 for example, have a width W and length L that can be generallythe same as the length and width of submount 12. For example, package 10can have a width W of between approximately 3.2 mm and approximately 3.6mm. Package 10 can have a length L of approximately 3.2 mm andapproximately 3.6 mm. For example, package 10 can have a width W ofapproximately 3.45 mm and a length L of approximately 3.45 mm. When a 1mm LED is used, package 10 can have a width W of approximately 3.5 mmand a length L of approximately 3.5 mm. When a 0.7 mm LED is used,package 10 can have a width W of approximately 3.2 mm and a length L ofapproximately 3.2 mm. It is further understood that submount 12 andouter perimeter of package 10 can have other shapes, as viewed fromabove, including circular, rectangular or other multiple sided shapes.

Since package 10 can be relatively small, but still emit a large amountof light, package 10 can have a large luminous flux to footprint ratio.As an example, an LED package that comprises an LED that generates adominant wavelength of between approximately 610 nm and approximately630 nm that can have a luminous flux of 90 lm or greater for a footprintarea of approximately 12 mm² can have a luminous flux to foot printratio of greater than approximately 7.5 lm/mm² for a red and/orred-orange light emitting LED. Thus, package 10 can produce a minimumluminous flux to footprint ratio of greater than approximately 7.5lm/mm². In some embodiments, package 10 can produce a minimum luminousflux to footprint ratio of approximately 3.75 lm/mm² or greater. In someembodiments, package 10 can produce a minimum luminous flux to footprintratio of approximately 8.3 lm/mm² or greater. For example, package 10can produce a minimum luminous flux to footprint ratio of betweenapproximately 3.75 lm/mm² and approximately 8.3 lm/mm² for a red and/orred-orange light emitting LED. For example, package 10 can produce aminimum luminous flux to footprint ratio of between approximately 5.9lm/mm² and approximately 7.9 lm/mm² for a red and/or red-orange lightemitting LED.

Similarly, LED packages 10 as described above used with at least one LED14 that can emit a dominant wavelength between approximately 610 nm andapproximately 630 nm can be efficient in its energy use by generating ahigh amount of lumens per unit of power used. For example, packages 10can be configured to generate a light output having a high amount oflumens per watt (lm/W) for a red and/or red-orange light emitting LEDsuch a wavelength range of between approximately 610 nm andapproximately 630 nm, or between 610 nm and approximately 620 nm. Insome embodiments, LED package 10 can be configured to generate a lightoutput of approximately 120 lm/W or greater for a red and/or red-orangelight emitting LED. In some embodiments, the lumens per watt generatedby LED package 10 can be, approximately 130 or greater for a red and/orred-orange light emitting LED.

LED package 10 as described above used with at least one LED 14 that canemit a dominant wavelength between approximately 610 nm andapproximately 630 nm such package 10 can also have a reduced thermalresistance as compared to conventional LED packages. For example,package 10 can be configured to have a thermal resistance ofapproximately 3° C./Watt or less. In some embodiments, the thermalresistance for LED package 10 can be approximately 2.5° C./Watt or less.LED package 10 as described above used with at least one LED 14 that canemit a dominant wavelength between approximately 610 nm andapproximately 630 nm such package 10 can thus also have a greateroperational lifetime as compared to conventional LED packages. Forexample and based upon operating conditions, LED package 10 can have apredicted L70 lifetime based upon standard modeling practices forlighting of at least 50,000 hours or greater at 350 milliamps and 85° C.In a further aspect, LED package 10 can be configured to have anoperational lifetime of at least 35,000 hours or greater at 350milliamps and 85° C.

FIGS. 7-9 show another embodiment of a package generally designated 110for one or more LEDs. As above, package 110 can comprise a submount 112that can have a top surface 116 and a bottom surface 118. Patternedconductive features such as top electrically conductive elements canreside on top surface 116 of submount 112. Top electrically conductiveelements can comprise a die attach pad 120 with an integral firstcontact pad 122 and second contact pad 124. One or more LEDs (not shown)can be mounted approximately at the center of attach pad 120. The one ormore LEDs can comprise at least one LED that can emit a dominantwavelength generally between approximately 600 nm and approximately 650nm, and more particularly between approximately 610 nm and approximately630 nm, to emit a red and/or red-orange light.

These patterned electrically conductive elements can provide conductivepaths for electrical connection to the LED using known contactingmethods. The LED can be mounted to attach pad 120 using known methodsand material for mounting such as using conventional solder materialsthat may or may not contain a flux material or dispensed polymericmaterials that may be thermally and electrically conductive. Attach pad120 and first and second contact pads 122, 124 can comprise materialssuch as metals or other conductive materials as outlined above. As notedabove, the LED can be attached to attach pad 120 with the polarity ofthe LED reversed such that the N-cladding of the LED is below themulti-quantum well and the P-cladding of the LED is above themulti-quantum well.

As above, a gap 126 seen in FIGS. 7 and 9 can be included between secondpad 124 and attach pad 120 down to the surface of submount 112. Gap 126can be in different shapes and widths. For example, as in the embodimentshown, gap 126 can extend in a straight line and/or can have turns, suchas angled turns therein. Such turns can be used as markers for placementof the one or more LEDs. Gap 126 can provide electrical isolationbetween attach pad 120 and second pad 124, which can be used to preventshorting of the signal applied to the LED. An electrical signal can beapplied to the LED through second pad 124 and first pad 122 with theelectrical signal on first pad 122 passing to the LED through attach pad120 and the signal from second pad 126 passing into the LED through wirebonds (not shown).

As above, in some embodiments an electrical signal can be applied topackage 110 by providing external electrical contact to first and secondbond pads 122, 124 such as by solder contacts or other conductive pathsto a PCB. Package 110 can be arranged for mounting using surface mounttechnology and having internal conductive paths; such as first andsecond surface mount pads 130, 132 that can be formed on back surface118 of submount 112 and vias 134 as shown in FIG. 8. As above, first andsecond surface mount pads 130, 132 can be at least partially alignedwith first and second contact pads 122, 124, respectively. It isunderstood that mounting pads 130, 132 and vias 134 can be arranged inmany different ways and can have many different shapes and sizes. It isalso understood that instead of vias, one or more conductive traces canbe provided on the surface of submount 112 between the mounting pads andcontact pads, such as along a side surface of the submount. Package 110can further comprise a bottom thermally conductive element that cancomprise a thermal pad 140 as shown in FIG. 8 on back surface 118 ofsubmount 112, between first and second mounting pads 130, 132. Thermalpad 140 can comprise a heat conductive material and can be in at leastpartial vertical alignment with the portion of attach pad 120 where theLED is to be attached for the reasons described above.

As shown in FIG. 9, a solder mask 136 made of conventional materials canbe included on top surface 116 of submount 112, at least partiallycovering attach pad 120 and first and second contact pads 122, 124, andat least partially covering gap 126. As above, solder mask 136 canprotect these features during subsequent processing steps and inparticular mounting the LED (not shown) to attach pad 120 and wirebonding. Solder mask 136 can serve as an insulating and protectivematerial that can reduce or prevent dangers associated with solder orother materials being deposited in undesired areas, which can result indamage to package 110 or result in electrical shorting. Solder mask 136can comprise an opening 136A for mounting the LED to attach pad 120 andfor attaching wire bonds (not shown) to second contact pad 124. Soldermask 136 can also comprise side openings 138 to allow convenientelectrical access to first and second contact pads 122, 124,respectively, for testing package 110 during fabrication. Solder mask136 can also have alignment holes that provide for alignment duringfabrication of package 110 and also allow for alignment when mounted inplace by an end user.

Additionally, as above, attach pad 120 can be provided with a symbol orindicator 136B to illustrate which side of LED package 110 should becoupled to a positive or negative aspect of the signal to be applied topackage 110 as shown in FIG. 7. Symbol 136B can ensure accurate mountingof LED package 110 to a PCB or other fixture, whether by machine orhand. In the embodiment shown the symbol 136B comprises a plus (+) signover first contact pad 122, indicating that the package 110 should bemounted with the positive of the signal coupled to the first surfacemount pad 132. Thus, the negative of the signal would then be coupled tosecond mount pad 130 and second conductive pad 124. It is understoodthat many different symbol types can be used and that a symbol can alsobe included on or over second conductive pad 124.

Further, as shown in embodiments of FIGS. 7-9, cut-outs 128 can beincluded in attach pad 120 to aid in alignment of the LED. Cut-outs 128can comprise many different shapes and sizes. In the embodiment shown,cut-outs 128 can provide generally a square outline. When mounting theLED chip to that attach pad 120, the corners of the LED chip can fit onthe inside edge of cut-outs 128 for proper alignment. Additionally,cut-outs 128 can be formed by part of gap 126.

LED packaging configured as packages 10 and 110 can provide a greaterminimum luminous flux than LED packages using conventional types ofpackaging. Thus, LED packages similar to LED packages 10 and 110 can beapproximately 10% to approximately 25% brighter than conventional LEDpackages for LEDs that generate a dominant wavelength between, forexample, approximately 610 and approximately 630 nm or betweenapproximately 610 and approximately 620 nm. Packages 10, 110 can beconfigured to generate a light output of a large amount of lumens perwatt. In some embodiments, LED packages 10, 110 can be configured togenerate a light output of approximately 120 lm/W or greater. In someembodiments, the lumens per watt generated by LED packages 10, 110 canbe approximately 130 lm/W or greater.

Further, such packages 10, 110 can be configured to have a lumenperformance when a current of approximately 350 mA is applied topackages 10, 110 that can be a minimum luminous flux of approximately 90lm or greater. For example, the LED(s) that can emit light having adominant wavelength of approximately 610 to approximately 630 nm canhave a luminance performance with the minimum luminous flux ofapproximately 95 lm or greater in packages 10, 110.

As stated above, LED packages 10, 110 as described above used with atleast one LED 14 that can emit a dominant wavelength betweenapproximately 610 nm and approximately 630 nm such packages 10, 110 canalso have a reduced thermal resistance as compared to conventional LEDpackages. For example, packages 10, 110 can be configured to have athermal resistance of approximately 3° C./Watt or less. In someembodiments, the thermal resistance for LED packages 10, 110 can beapproximately 2.5° C./Watt or less. Thereby, due to the improveperformance characteristics described above, LED packages 10, 110 thathave at least one LED that can emit a dominant wavelength betweenapproximately 600 nm and approximately 650 nm can thus also have greateroperational lifetimes as compared to conventional LED packages. Forexample and based upon operating conditions, LED packages 10, 110 canhave a predicted L70 lifetime based upon standard modeling practices forlighting of at least 50,000 hours or greater at 350 milliamps and 85° C.In a further aspect, they can have an operational lifetime of at least35,000 hours or greater at 350 milliamps and 85° C.

Embodiments of the present disclosure shown in the drawings anddescribed above are exemplary of numerous embodiments that can be madewithin the scope of the appended claims. It is contemplated that theconfigurations of LED packages and methods disclosed herein can comprisenumerous configurations other than those specifically disclosed.

1. A light-emitting die (LED) package comprising: a ceramic submount; anLED disposed on the submount, the LED operable for emitting a dominantwavelength between approximately 610 nm and approximately 630 nm; a lensdisposed over the LED; and the LED package configured to have a minimumluminous flux that is approximately 90 lm or greater when an electricalsignal that is applied to the LED package comprises a current ofapproximately 350 mA.
 2. The LED package of claim 1, wherein thesubmount comprises aluminum nitride.
 3. The LED package of claim 1,wherein the lumen performance comprises a minimum luminous flux that isapproximately 100 lm or greater when the electrical signal comprises acurrent of approximately 350 mA.
 4. The LED package of claim 1, whereinthe LED package is configured to generate a light output ofapproximately 120 lumens/watt or greater.
 5. The LED package of claim 1,wherein the LED package is configured to generate a light output ofapproximately 130 lumens/watt or greater.
 6. The LED package of claim 1,wherein the LED package is configured to have a thermal resistance thatis approximately 3° C./Watt or less.
 7. The LED package of claim 1,wherein the LED package is configured to have a predicted L70 lifetimeof at least 50,000 hours or greater at 350 milliamps and 85° C.
 8. TheLED package of claim 1, wherein a minimum luminous flux to footprintratio for the LED package is greater than approximately 5.8 lm/mm² whenthe electrical signal comprises a current of approximately 350 mA. 9.The LED package of claim 1, wherein the lens is of a radius size ofapproximately 1.275 mm or greater.
 10. The LED package of claim 1,wherein the lens is molded over the LED.
 11. The LED package of claim 1wherein the submount comprises a top surface and a bottom surface, andthe LED package comprises: a plurality of top electrically conductiveelements on the top surface of the submount; the LED disposed on atleast one of the top electrically conductive elements; and a bottomthermally conductive element on the bottom surface of the submount forconducting heat from the submount.
 12. The LED package of claim 11,wherein the submount comprises aluminum nitride.
 13. A light-emittingdie (LED) package comprising: a ceramic submount; an LED disposed on thesubmount, the LED operable for emitting a dominant wavelength betweenapproximately 610 nm and approximately 630 nm; a lens disposed over theLED; and wherein the LED package is configured to generate a lightoutput of approximately 120 lumens per watt or greater.
 14. The LEDpackage of claim 13, wherein the submount comprises aluminum nitride.15. The LED package of claim 13, wherein the LED package is configuredto generate a light output of approximately 130 lumens per watt orgreater.
 16. The LED package of claim 13, wherein the LED package isconfigured to have a thermal resistance that is approximately 3° C./Wattor less.
 17. The LED package of claim 13, wherein the LED package isconfigured to have a predicted L70 lifetime of at least 50,000 hours orgreater at 350 milliamps and 85° C.
 18. The LED package of claim 13,wherein the lens is of a radius size of approximately 1.275 mm orgreater.
 19. The LED package of claim 13, wherein the lens is moldedover the LED.
 20. The LED package of claim 13 wherein the submountcomprises a top surface and a bottom surface, and the LED packagecomprises: a plurality of top electrically conductive elements on thetop surface of the submount; the LED disposed on one of the topelectrically conductive elements; and a bottom thermally conductiveelement on the bottom surface of the submount for conducting heat fromthe submount.
 21. The LED package of claim 20, wherein the submountcomprises aluminum nitride.
 22. A light-emitting die (LED) packagecomprising: a submount comprising aluminum nitride; an LED disposed onthe submount, the LED operable for emitting a dominant wavelengthbetween approximately 610 nm and approximately 630 nm; and a lensdisposed over the LED.
 23. The LED package of claim 22 wherein the lensis a molded lens.
 24. The LED package of claim 23 wherein the moldedlens is an overmolded lens.
 25. The LED package of claim 22, wherein theLED package is configured to have a thermal resistance that isapproximately 3° C./Watt or less.
 26. A method of operating alight-emitting die (LED) package comprising: providing an LED packagecomprising: a ceramic submount; an LED disposed on the submount, the LEDoperable for emitting a dominant wavelength between approximately 610 nmand approximately 630 nm; and a lens disposed over the LED; applying anelectrical signal to the LED package; and generating a light output fromthe LED in the LED package that is approximately 120 lumens per watts orgreater.
 27. The method of claim 26, wherein the step of applying anelectrical signal comprises applying a current of approximately 350 mAand generating a minimum luminous flux is approximately 90 lm orgreater.
 28. The method of claim 26, wherein a minimum luminous flux tofootprint ratio for the LED package is greater than approximately 5.8lm/mm² when the electrical signal comprises a current of approximately350 mA.
 29. The method of claim 26, wherein a thermal resistance of theLED package is approximately 3° C./Watt or less.
 30. The method of claim26, wherein the LED package is configured to have a predicted L70lifetime of at least 50,000 hours or greater at 350 milliamps and 85° C.31. The method of claim 26, wherein the lens is molded over the LED. 32.A light-emitting die (LED) package comprising: a submount; an LEDdisposed on the submount, the LED operable for emitting a dominantwavelength between approximately 610 nm and approximately 630 nm; and athermal resistance of approximately 3° C./Watt or less.
 33. The LEDpackage of claim 32 wherein the lens is a molded lens.
 34. The LEDpackage of claim 33 wherein the molded lens is an overmolded lens.